CN102472472A - A lighting device and a lens suitable for such a lighting device - Google Patents

Abstract

The lighting device (1) comprises a light source (2) and a lens (3, 23, 33, 43, 53, 63) positioned in front of the light source (2). The lenses (3, 23, 33, 43, 53, 63) are provided with a light-incidence surface on the side facing the light source (2) and with a light-exit surface (14, 38) on the side facing away from the light source (2). The lenses (3,23,33,43,53,63) consist of several elongated light-guiding elements (4,24,34,54,64) interconnected in ribbon form, the first ends of which (7,27,37,57) The spaced apart second ends ( 5 , 25 , 35 , 55 , 65 ) respectively include a light entry surface and a light exit surface. The light beam emitted by the light source (2) is transmitted from the first end (7,27,37,57) to the spaced apart Second end (5,25,35,55,65).

Description

Lighting device and lens suitable for use in such lighting device

technical field

The invention relates to a lighting device comprising a light source and a lens in front of the light source, the lens being provided with a light entrance surface on the side facing the light source and with a light exit surface on the side facing away from the light source.

The invention also relates to a lens.

Background technique

Such a lighting device known from EP2009345 A2 comprises a first optical refractive element arranged around the peripheral edge and a second optical refractive element in the center of the lens. The reflector is positioned between the light source, such as a light emitting diode (LED), and the lens. The forward emitting part of the LED's light goes directly to the lens, while the side emitting part is reflected by the reflector before it goes to the lens.

A disadvantage of this known lighting device is that the perceived luminance of the lens is of the same order as the luminance of the light source. In the case of high power LEDs, the luminaire will emit intense and blinding light.

Due to the extremely high brightness of LEDs, it is difficult to use such lighting devices with high power LEDs for general indoor lighting. To avoid direct exposure of the viewer to the high brightness of the LEDs, a brightness converter can be added. However, such brightness converters have the disadvantage that they lead to a reduction in optical efficiency and an increase in the cost of the lighting device.

Contents of the invention

It is an object of the present invention to provide a lighting device with a simple structure, relatively high optical efficiency and brightness conversion for avoiding glare.

This object is achieved with a lighting device according to the invention, in that the lens comprises several elongated light-guiding elements interconnected in strip form, the first and spaced-apart second ends of which respectively comprise a light entrance surface and a light exit surface, and are controlled by a light source. The emitted light beam is transmitted from the first end to the spaced apart second end by total internal reflection in the elongated light guiding element.

Due to the strip-shaped elongated light-guiding element and the spaced-apart second ends, a lens with an open structure is obtained. Due to the strip-shaped elongated light-guiding element, the length from the first end to the second end in the first direction is of the same order of magnitude or shorter than the length of the elongated light-guiding element in the second direction perpendicular to the first direction. much smaller. The open structure provides a relatively large light exit surface compared to the light entry surface. The brightness of the light source is distributed over a relatively large light exit surface, whereby the observed brightness is strongly reduced. The light beam from the light source is transmitted by total internal reflection, whereby a high optical efficiency of the lens is obtained. Lighting devices with such lenses are suitable for a wide range of indoor and outdoor applications.

An embodiment of the lighting device according to the invention is characterized in that at least the strip-shaped second ends of the elongated light guiding element extend parallel to each other.

In this way the light exit surface will have a rectangular shape, whereby the light emitted by the lighting device may appear similar to the light emitted by an elongated fluorescent tube.

Preferably, the elongated light guide elements extend parallel to each other from the first end to the second end, which makes it possible to manufacture the lens by extrusion (extrusion), so that it can be realized in the second direction perpendicular to the first direction from A relatively large length from the first end to the second end.

Devices with such lenses are suitable as lights for shop lighting or as lights or tunnel lighting for buses, trains or airplanes. Such lenses are also suitable for use in waterproof luminaires, since only the small incident area where one or more LEDs are located must be waterproof along with the ends on both sides.

Another embodiment of the lighting device according to the invention is characterized in that at least the second end of the elongated light guiding element is an annular band positioned concentrically with respect to each other.

In this way the light exit surface will have a cylindrical shape, whereby the light emitted by the lighting device can appear similar to the light emitted by an incandescent bulb.

Preferably, the elongated light guiding elements are annular from the first end to the second end such that each elongated light guiding element is cup-shaped.

Devices with such lenses are suitable for home lighting or as downlighters for office lighting or shop lighting.

A further embodiment of the lighting device according to the invention is characterized in that at least a part of the elongated light guiding elements are interconnected at least near the first end and/or the second end.

Thus, a continuous light entry surface and/or exit surface can be obtained, provided the lens has a smooth appearance. The area where the elongated light-guiding elements are interconnected is preferably as small as possible to prevent interference with total internal reflection in the elongated light-guiding elements.

Another embodiment of the lighting device according to the invention is characterized in that the area of the light exit surface of the lens is at least 100 times and preferably at least 10000 times larger than the light emitting area of the light source.

Due to the increase of the light exit surface relative to the light emitting surface of the light source, a reduction in perceived brightness is obtained. Depending on the desired brightness, the ratio between the light incident surface and the light emitting surface and the number and shape of the elongated light guiding elements are chosen.

Another embodiment of the lighting device according to the invention is characterized in that the surface of the first end of the elongated light guiding element extends substantially perpendicularly to the light beam of the light source directed at said elongated light guiding element.

All light emitted by the light source towards the elongated light guiding element will enter the elongated light guiding element so that the optical efficiency will be optimal.

A further embodiment of the lighting device according to the invention is characterized in that the light exit surface has an inclined, convex or concave shape.

The shape of the light exit surface further improves the light emitted by the lighting device, its visual appearance and to a large extent determines the beam pattern emerging from the lighting device. This is particularly beneficial for applications where beam control is important, such as in automotive headlight systems, for example for generating dark beams.

Another embodiment of the lighting device according to the invention is characterized in that the lens is made of acrylic, polycarbonate or other transparent material.

From such materials, relatively inexpensive lenses can be easily produced.

Another embodiment of the lighting device according to the invention is characterized in that the lens is made by injection molding or extrusion.

This manufacturing process is relatively easy. In the case of injection molding, the lens can be assembled from several parts to avoid draft angle problems.

Description of drawings

The invention will be explained in more detail with reference to the accompanying drawings, in which:

Figures 1A and 1B are respectively a sectional view and a perspective top view of a first embodiment of a lighting device according to the invention,

Fig. 2 is a cross-sectional view of the lens of the lighting device as shown in Fig. 1, wherein the light beam is emitted by the light source and internally reflected by the elongated light-guiding element of the lens,

Fig. 3 is a perspective view of a second embodiment of a lighting device according to the invention,

Fig. 4A is a cross-section of a third embodiment of a lighting device according to the invention,

4B-4D are different embodiments of the second end of the elongated light guiding element,

Figure 5 is a perspective bottom view of a third embodiment of the lighting device as shown in Figure 4A,

Fig. 6 is a cross-section of a fourth embodiment of a lighting device according to the invention,

Fig. 7 is a cross-section of a fifth embodiment of a lighting device according to the invention,

Fig. 8 is a cross-section of a sixth embodiment of a lighting device according to the invention.

Detailed ways

In the drawings, the same parts are indicated by the same reference numerals.

Figures 1A, 1B and 2 show a first embodiment of a lighting device 1 according to the invention. The lighting device 1 includes a high-power LED 2 and a lens 3 as a light source. The lens 3 comprises several elongated light guiding elements 4 which are interconnected by means of a plate 6 near a second spaced apart end 5 . The first end 7 of the elongated light guiding element is located adjacent to the LED 2. The first ends 7 are spaced apart such that the distance between the first ends 7 is much smaller than the distance between the second ends 5 at the plate 6 . The elongated light guiding element 4 is cup-shaped such that the first end 7 and the second end 5 form an annular band. Each of the first ends 7 of the elongated light guiding element 4 is provided with a light receiving surface 8 . The light-receiving surfaces 8 of all elongated light-guiding elements 4 form the light-incidence surfaces of the lenses 3 . The light receiving surfaces 8 are positioned relative to each other in such a way that all light beams of the LEDs 2 will enter one of the light receiving surfaces 8 and no light beams will enter the openings 9 between the elongated light guiding elements 4. Preferably, each light receiving surface 8 extends substantially perpendicular to the light beam entering said light receiving surface 8 . The two centrally located elongated light-guiding elements 4 are connected to each other by their second ends 7 , whereas just outside the first ends 7 the elongated light-guiding elements 4 are spaced apart. Between the elongated light guiding elements 4 there are openings 9 which become wider in a direction away from the LED 2. The strip-shaped elongated light guide element 4 is relatively long in the direction from the LED 2 towards the plate 6 and in the circumferential direction. The elongated light guiding element 4 is curved and dimensioned such that the light beams 10, 11 entering the light receiving surface 8 are completely reflected inside the elongated light guiding element 4 by the inner and outer surfaces 12, 13 of the elongated light guiding element 4 until the light beam 10 , 11 reach the second end 5 of the elongated light guiding element 4 and leave the second end 5 through the light exit surface 14 of the plate 6 .

Due to the elongated light guide elements 4, their curved shape and the openings 9 between the elongated light guide elements 4, the light exit surface 14 of the plate 6 interconnecting the second ends 5 of the elongated light guide elements 4 is larger than that produced by the elongated light guide elements 4. The light receiving surface 8 of the element 4 forms a much larger light incident surface. Preferably, the light exit surface 14 is at least 100 times and more preferably at least 10000 times larger than the light emitting surface 2 ′ of the LED 2 . The light-emitting surface 2' of the LED 2 is, for example, 1x1 mm to 3x3 mm, and the luminance is, for example, 10 ⁷ cd/m ² . Preferably, the perceived brightness is approximately 10 ⁴ cd/m ² to 5x10 ⁴ cd/m ² . Therefore, the light exit surface of the lens should preferably be approximately 5×10 ⁻⁴ m ² to 10 ⁻² m ² . The number of elongate light guiding elements 4 is preferably at least three and at most fifty. The brightness of LED 2 is strongly fragmented and a much lower brightness is perceived by the viewer. However, due to total internal reflection, the optical efficiency of the lens 3 is high and almost no light is lost.

The lens 3 is made of acrylic, polycarbonate or other transparent material and is preferably made by injection moulding. It can be made from parts to overcome draft angle problems during the injection molding process.

Fig. 3 shows a second embodiment of the lens 23 of the lighting device according to the invention. Lens 23 has a similar cross-section as lens 3 and as shown in FIG. 1 . However, instead of a circular shape, the lens 23 has a more rectangular shape. The lens 23 comprises several strip-shaped elongated light guiding elements 24 extending parallel to each other. The elongated light guiding elements 24 are interconnected near the second end 5 by means of a rectangular plate 26 . The first end 27 of the elongated light guiding element 24 is located adjacent to a channel 31 in which a number of LEDs 2 can be placed in a row or in an array. The first ends 27 are spaced apart by a much smaller distance between the first ends 27 than the distance between the second ends 25 , ie where they enter the plate 26 . Each of the first ends 27 of the elongated light guiding elements 24 is provided with a light receiving surface 28 , the light receiving surfaces 28 of all the elongated light guiding elements 24 thus forming the light incident surface of the lens 23 . The light receiving surfaces 28 are positioned relative to each other in such a way that all light beams of the LED 2 will enter one of the light receiving surfaces 28 and no light beams will enter the openings 29 between the elongated light guiding elements 24.

The light beams of the rows of LEDs in the channel 31 will be guided by total internal reflection through the elongated light guiding element 24 in the manner shown in FIG. 2 . The lens 23 can be produced by means of extrusion, so that relatively long lenses of eg 1 meter in the direction of extrusion can be obtained. Such lenses can be used, for example, in the lighting of buses, trains, airplanes or parking garages.

The total light-emitting surface of a row or array of LEDs 2 is the sum of the light-emitting surfaces 2′ of all LEDs 2. Preferably, the light exit surface of the lens 23 at the plate 26 is at least 100 times and more preferably at least 10000 times larger than the total light emitting surface of the LED 2.

Other shapes of the lens can be made by grinding the outer surface of the lens 23 .

Figures 4A and 5 show a third embodiment of a lens 33 of a lighting device according to the invention. The lens 33 comprises a cup-shaped curved elongated light guiding element 34 . The first ends 37 of the elongated light guiding elements 34 are positioned against each other and form the light entrance surface 36 . The second ends 35 of the elongated light guiding elements 34 are spaced apart such that the distance between the second ends 35 is substantially greater than the distance between the first ends 37 . Openings 39 are located between the elongated light guiding elements 34 . Near the second end 35 the elongated light guiding element 34 is provided with a light exit surface 38 such that the light exit surface of the lens 33 is formed by the area where the light exit surface 38 is located. The area of the light entry surface 36 is much smaller than the area of the light exit surface 38 of the lens 33, whereby the perceived brightness of the lighting device is much lower than that of the LED 2 located opposite the light entry surface 36. The second end 35 of the elongated light guiding element 34 may be provided with a convex light exit surface 40, a concave light exit surface 41 or an inclined light exit surface 42 as shown in FIGS. 4B, 4C, 4D respectively, to modify the emitted light as desired. .

Fig. 6 shows a fourth embodiment of a lens 43 of a lighting device according to the invention. Lens 43 differs from lens 33 in that second end 35 lies in a convex plane rather than a generally flat plane.

Fig. 7 shows a fifth embodiment of a lens 53 of a lighting device according to the invention. The lens 53 differs from the lens 33 in that the thickness of the elongated light guiding elements 54 near the first end 57 is greater outside the lens 54 than inside, while the thickness of all the elongated light guiding elements 54 near the second end 55 is equal.

Fig. 8 shows a sixth embodiment of a lens 63 of a lighting device according to the invention. Lens 63 differs from lens 53 in that the second end 65 of the outer cup-shaped elongated light guiding element 64 is flared such that its light exit surface 68 faces away from the light exit surface 58 of the other elongated light guiding element 54 .

It is also possible to make more rectangular lenses, such as that shown in Figure 3 with the cross-sections shown in Figures 6, 7 or 8.

It is also possible to extend the outer elongate light guiding element 34 so that the second end lies in a convex plane, a corrugated plane or any differently shaped plane.

It is also possible to provide the light exit surface of the elongated light guide element with a microstructure, such as a frosted structure or a diffuse structure, to further improve the light distribution.

It is also possible that the elongated light guiding elements are connected to each other by light guiding material, or opaque material or a holder, somewhere between the first and second ends.

Preferably, the elongate light guiding element is rigid. However, it is also possible to manufacture flexible elongated light guiding elements such that the position of the light exit surface of each elongated light guiding element can be changed as desired.

Claims (10)

1. lighting apparatus (1) that comprises light source (2) and be positioned at the lens (3,23,33,43,53,63) of light source (2) front, lens (3; 23,33,43,53,63) on the side of light source (2), being provided with light incident surface and on side, being provided with light exit surface (14,38), it is characterized in that away from light source (2); Lens (3,23,33,43,53,63) comprise the elongate light guides element (4,24 of some banded interconnection; 34,54,64), its first end (7,27,37; 57) and isolated second end (5,25,35,55,65) comprise light incident surface and light exit surface respectively, and by light source (2) emitted light beams (10; 11) in elongated photocon (4,24,34,54,64) through total internal reflection by from first end (7,27; 37,57) be transferred to isolated second end (5,25,35,55,65).

2. according to the lighting apparatus (1) of claim 1, it is characterized in that banded at least second end of elongate light guides element (4,24,34,54,64) extends in parallel to each other.

3. according to the lighting apparatus (1) of claim 1, it is characterized in that at least the second end of elongate light guides element (4,24,34,54,64) is the endless belt of relative to each other locating with one heart.

4. according to each lighting apparatus (1) in the aforementioned claim, it is characterized in that at least a portion of elongate light guides element (4,24,34,54,64) interconnects at least near first end and/or second end.

5. according to each lighting apparatus (1) in the aforementioned claim, the area that it is characterized in that the light exit surface of lens (3,23,33,43,53,63) is at least 100 times and preferably at least 10000 times of light-emitting area of light source (2).

6. according to each lighting apparatus (1) in the aforementioned claim, it is characterized in that elongate light guides element (4,24; The optical receiving surface (8 of first end 34,54,64); 28) be basically perpendicular to the said elongate light guides element (4,24,34 of sensing; The light beam of light source 54,64) (2) and extending.

7. according to each lighting apparatus (1) in the aforementioned claim, it is characterized in that light exit surface has inclination, protruding or recessed shape.

8. according to each lighting apparatus (1) in the aforementioned claim, it is characterized in that lens (3,23,33,43,53,63) are processed by propylene, Merlon or other transparent materials.

9. according to each lighting apparatus (1) in the aforementioned claim, it is characterized in that lens (3,23,33,43,53,63) process through injection-molded or extruding.

10. one kind is suitable for use in according to the lens (3,23,33,43,53,63) in each the lighting apparatus (1) in the aforementioned claim.

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